Under the Chemical Substances Control Law (CSCL) in Japan, initial hazard information tor existing chemical substances has been collected by the Ministry of Health, Labour and Welfare, Japan (MHLW) to assess potential initial risks to human health. We have reviewed all collected toxicity information pertaining to acute toxicity, repeated dose toxicity, genotoxicity, and/or reproductive/developmental toxicity and performed hazard assessments. Approximately 150 substances are currently undergoing review and assessment. For clarification and evaluation of each toxicity study, we have created a dossier (a collection of study data containing a detailed summary of the methods, results, and conclusions of each study) in English using the International Uniform Chemical Information Database (IUCLID) version 5. The IUCLID dossier format is widely used and has been accepted as one of the most beneficial formats for providing summarized chemical substance toxicity assessments. In this report, as a contribution to our ongoing hazard assessment activity, we present summary hazard information related to the potential human health effects of the following 5 chemical substances: 4-chlorobenzoyl chloride (CAS: 122-01-0); benzenesulfonic acid, 4-hydroxy-, tin (2+) salt (CAS: 70974- 33-3); chlorocyclohexane (CAS: 542-18-7); 1,3-cyclohexanedimethanamine (CAS: 2579-20-6); and 1,3,5-triazine-2,4,6 (1H,3H,5H) -trithione (CAS: 638-16-4). The IUCLID dossiers created for these 5 chemical substances will be made available via the Japan Existing Chemical Data Base (JECDB) at <http://dra4.nihs.go.jp/mhlw_data/jsp/SearchPageENG.jsp>. Additional human health hazard information on existing chemical substances will be provided using the same methodology and website when it is available.